Although there are no guarantees in life, locking your bike every time you leave it unattended is the best way to prevent somebody from walking away with your ride.

Here are a few tips to keep in mind:

U-locks are the most reliable. However, some models of bike locks have been found to be susceptible to security breaches with a plastic pen. Locks with axial pin tumblers that have a circular keyhole and use a tubular key are affected. This includes locks from most manufacturers. Look for U-locks with flat keys or without axial pin tumblers.

Even better is a U-lock and cable lock. Cheap chain locks and combination locks will only prevent a theft of convenience. A pro will snip that wimpy chain and be gone with your bike in a flash.

Fill your U-lock with your wheels and frame to help prevent thieves from using a jack to pry your lock apart. Try to keep the lock high off the ground with its keyhole pointing down; this orientation makes it more visible, and harder to smash or pick open.

Lock all accessories, including your wheels, helmet, seat, and frame (thieves love anything attached by a quick-release), if leaving your bike for extended periods of time in a public place (or even at home).

Always lock your bike to an immovable object avoid small trees, wooden posts, chain-link fences, and unsecured bike racks. If you are locking your bike to a road sign, make sure the sign is firmly secured to the ground (many signposts are held in place with a set screw that is easily undone).

Lock your bike up with other bikes in a well-lit public area. If your bike is the most secured one in a group, thieves will most likely ignore it.

Expensive bikes are a prime target, especially when they are parked in the same place every day. Mix it up try locking your bike in different places or moving it during the day.

Insurance
If you are riding a very expensive bike, there is a good chance it is not covered under your home-owners or renters insurance. Even if it is, there is most likely a limit on how much you can claim. Check with your insurance company. Chances are you will have to buy separate bike insurance to cover a bike worth more than a few hundred bucks.

Take a photo of your bike, note the serial number, and keep the original sales receipt. Additionally, always keep the receipts for new or upgraded components. It will help you settle any insurance claims.